A network of six world-wide observatories that monitors solar oscillations (see helioseismology). The oscillations are detected from precise measurements of the Doppler shifts in small areas of the Sun. The network started operation in 1995 at sites in the Canary Islands (Teide Observatory), Western Australia (Learmonth Solar Observatory), California (Big Bear Solar Observatory), Hawaii (Mauna Loa Solar Observatory), India (Udaipur Solar Observatory), and Chile (Cerro Tololo Inter-American Observatory). The network is managed by the US National Solar Observatory and has its headquarters in Tucson, Arizona.

http://gong.nso.edu/ Official GONG website.